They say it could dilute targeting the true causes of poverty - where income remains the key variant.

If child poverty is rising as a result of government policies, then it’s a rethink of government decisions not definitions that’s needed. The relative income poverty measure is the single best indicator of whether ‘we’re all in together.

– Alison Garnham, chief executive of the Child Poverty Action Group

There is no getting away from the fact that a child's family income is fundamental to their future life chances.

While a holistic approach to tackling child poverty is important, income will always be vital for ending child poverty.

– Enver Solomon, chair of the End Child Poverty coalition

Debating how child poverty is measured must not distract from the urgent need for action to improve the life chances of children currently growing up in families that are languishing below the breadline.

Barnardo's urges the Government to keep measuring income but also to help families climb their way up and out of the poverty trap.

Secretary of State for Work and Pensions Iain Duncan Smith Credit: Anthony Devlin/PA Archive

Iain Duncan Smith will today seek to reassure critics that he is committed to ending child poverty but insist that "meaningful and accurate" measures must replace "arbitrary" household income targets.

The Work and Pensions Secretary will launch a consultation on controversial plans to move away from the poverty indicator introduced by Labour, which defines it as those children living in households with less than 60% of the median income.